Edward Snowden, is seen live from Moscow, at the Norwegian PEN event ‘Waiting for Snowden’ in Oslo on 18 November 2016.
Photograph: Berit Roald/AFP/Getty Images

Edward Snowden “has had and continues to have contact” with Russian intelligence services since arriving in Moscow three years ago, newly declassified portions of a congressional report released on Thursday claim.

The House intelligence committee released the declassified portions to provide what the panel’s chairman called “a fuller account of Edward Snowden’s crimes and the reckless disregard he has shown for US national security”.

The report is highly critical of Snowden, the former NSA contractor who revealed the scale of the NSA’s surveillance program, claiming that he did not attempt to communicate his concerns to his supervisors before providing the Guardian with top-secret NSA documents.

However, the report’s credibility was immediately condemned by Snowden’s lawyer Ben Wizner. He dismissed the report and insisted that Snowden acted to inform the public.

“The House committee spent three years and millions of dollars in a failed attempt to discredit Edward Snowden, whose actions led to the most significant intelligence reforms in a generation,” Wizner said. “The report wholly ignores Snowden’s repeated and courageous criticism of Russian surveillance and censorship laws. It combines demonstrable falsehoods with deceptive inferences to paint an entirely fictional portrait of an American whistleblower.”

The political motivation of the report was called into question in September when a four-page executive summary was released on the eve of the premiere of Oliver Stone’s biopic on the whistleblower, claiming that Snowden “damaged” national security, without providing evidence to support the claim.

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Barton Gellman, the three-time Pulitzer prize winner who used Edward Snowden’s disclosures in his reporting on the NSA while at the Washington Post, dismantled the report’s claims when the executive summary was published, calling it “aggressively dishonest” and “trifling”.

On Thursday as the declassified portions of the report were published in full, Snowden, the former national security whistleblower, pushed back further against the accusations in a series of tweets.

“Unsurprising that HPSCI’s report is rifled with obvious falsehoods. The only surprise is how accidentally exonerating it is,” Snowden tweeted.

Edward Snowden (@Snowden)

After three years of investigation and millions of dollars, they can present no evidence of harmful intent, foreign influence, or harm. Wow.

The panel’s top Republican and Democrat joined in castigating Snowden, who in 2013 revealed US government efforts to hack into the data pipelines used by US companies to serve customers overseas. The programs collected the telephone metadata records of millions of Americans and examined emails from overseas.

Snowden subsequently fled to Hong Kong and then to Russia to avoid prosecution, after his disclosures triggered international outrage over the reach of US spy operations.

The report pointed to statements in June 2016 by the deputy chairman of the defense and security committee in the Russian parliament’s upper house, who asserted that “Snowden did share intelligence” with the Russian government.

The Pentagon found 13 undisclosed “high risk” security issues caused by Snowden’s disclosure to media outlets, including the Guardian, of tens of thousands of the US eavesdropping agency’s most sensitive documents, according to the congressional inquiry.

If the Chinese or Russians obtained access to materials related to these issues, “American troops will be at greater risk in any future conflict,” the report said.

The committee chairman, the Republican congressman Devin Nunes, said it “will take a long time to mitigate the damage” Snowden allegedly caused.

The committee’s top Democrat, Adam Schiff of California, said Snowden was not a whistleblower as he and his defenders claim. “Most of the material he stole had nothing to do with Americans’ privacy, and its compromise has been of great value to America’s adversaries and those who mean to do America harm,” Schiff said.

But on Twitter, Snowden added that the report itself admitted that he “purged and abandoned” hard drives containing the material, rather than bring them to Russia.

Edward Snowden (@Snowden)

Bottom line: this report's core claims are made without evidence, and are often contrary to both common sense and the public record.

Release of the report comes as the intelligence community has accused Russia of interfering in the US elections.

Snowden’s supporters have pressed Barack Obama to pardon him before he leaves office in late January. But the details in the intelligence committee’s report, coupled with the intense focus on Russia’s hacking of Democratic emails, could doom the push for a pardon.